1. Field of the Invention
The present invention relates to apparatus and methods for drilling and/or completing wells in the subterranean. In another aspect, the present invention relates to apparatus and methods for isolating geological formations in wells and isolating well casing annuluses. In even another aspect, the present invention relates to apparatus and methods for producing from side tracked wells drilled from the bore of previously drilled wells. In still another aspect, the present invention relates to apparatus and methods for isolating defective casing in an existing wellbore, isolating a liner top, or isolating a zone.
2. Description of the Related Art
Oil fields are usually produced by drilling wells to one or more large reservoirs or to vertically-separated smaller reservoirs encountered by an individual wellbore. The costs of a well are the costs of drilling and the cost of completion. Whereas drilling is the actual creation of the wellbore, completion is the process of inserting casing, tubing, and tubular accessories into the well to allow the oil or gas to be drawn out and stored for use. It is common practice in completing a well to run a string of protective casing into the wellbore and then to run production tubing inside the casing to one large reservoir or to vertically-separated production zones encountered by the wellbore. Once the oil or gas bearing formations penetrated are depleted, the well has lost its usefulness.
In many instances, small reservoirs in other areas of the oil bearing formation in the vicinity of the wellbores may not be depleted. Unfortunately, it is expensive to drill out through the side of the well (sidetrack) through the existing well casing using conventional sidetracking methods. Such methods require that the tubing be removed, a section of the casing be milled out and a drill run back down through the casing and directed outward through the milled-out section to drill a directional well from the casing outwardly to an area from which additional hydrocarbons may be recovered. Since these techniques are relatively expensive, the amount of potential hydrocarbon recovery required to justify such sidetracking operations is relatively large. Since, in many instances, areas of potentially recoverable hydrocarbons containing less than the amount required to justify this additional expense are known, it is desirable that a more economical method be developed to enable the economical recovery of these smaller quantities of hydrocarbons. The smaller quantities of hydrocarbons may, in fact, be quite sizeable.
One problem that can reduce the cost effectiveness of a side tracked well is that the new tubing inserted in the original well casing in the process of drilling the lateral well usually is of smaller diameter than the tubing of the original well to provide room for passing the tubing down the casing and into the lateral wellbore. This smaller diameter of tubing reduces the rate at which oil or gas can be brought to the surface.
Another problem associated with conventional sidetracking methods is the frequent need to run and cement an additional set of casing above or through the proposed producing formation to isolate the side tracked well from such problems as adjacent water-bearing formations.
There is a need in the art for apparatus and method for drilling and/or completing a well.
There is another need in the art for improved apparatus and methods for drilling and/or completing a well, which do not suffer from all of the deficiencies of the prior art.
There is even another need for apparatus and methods for performing cost-effective side tracked well completions.
There is still another need in the art for apparatus and methods for accessing small reservoirs with side tracked completions, which do not suffer from the disadvantages of the prior art apparatus and methods, such as the need to run and cement an additional set of casing above or through the proposed producing formation.
There is yet another need in the art for apparatus and methods for isolating formations and well casing annuluses.
There is even still another need in the art for apparatus and methods for isolating formations and well casing annuluses which address at least some of the deficiencies of the prior art, such as obtaining reduced flow rates because of the necessity of running smaller tubular strings to operate within existing wells.
These and other needs in the art will become apparent to those of skill in the art upon review of this specification, including its drawings and claims.
It is an object of the present invention to provide for an improved apparatus and method for drilling and/or completing a well.
It is another object of the present invention to provide for apparatus and methods for performing cost-effective side tracked well completions.
It is even another object of the present invention to provide for apparatus and methods for accessing small reservoirs with side tracked completions, which do not suffer from the disadvantages of the prior art apparatus and methods, such as the need to run and cement an additional set of casing above or through the proposed producing formation. It is an object of the present invention to provide for apparatus and methods for isolating formations and well casing annuluses.
It is still another object of the present invention to provide for apparatus and methods for isolating formations and well casing annuluses which address at least some of the deficiencies of the prior art, such as obtaining reduced flow rates because of the necessity of running smaller tubular strings to operate within existing wells.
These and other objects of the present invention will become apparent to those of skill in the art upon review of this specification, including its drawings and claims.
According to one embodiment of the present invention, there is provided a packer system which generally includes an expandable tubing and at least one elastomeric expanding element encircling said tubing. In a more specific non-limiting embodiment of this embodiment, the expandable packer system includes expandable tubing with separated transverse external bands of elastomeric elements adhering to the tubing with each of the two transverse edges of each band anchored by single centralizer rings, which also serve to maintain a packer in the center of a wellbore or casing.
According to another embodiment of the present invention, there is provided a work string assembly for use in a subterranean wellbore. The assembly generally includes a work string suitable for insertion into the wellbore. The work string also includes a pig launcher connected to the work string. The work string even also includes an expandable tubing connected to the pig launcher and at least one elastomeric expanding element encircling said tubing.
According to even another embodiment of the present invention, there is provided a method for expanding a packer in a well. The method generally includes positioning a packer system, as described above, in a subterranean well, and then passing an expansion pig through the expandable tubing to abut the elastomeric elements against the well wall.